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Displaying posts with tag: Databases (reset)
Query Reviews (part 2): pt-query-digest

Query reviews (part 1): Overview

The 1st post in the series gave an overview of what a query review is and the value they can bring you. So now let’s talk about how one is done, specifically, how to do a query review using pt-query-digest.

The point of a query review is that it is a comprehensive review of queries. Imagine if you could get a list of all queries that run on your system, and then you systematically looked at each query to determine if it is optimized. That is the basic concept behind a query review.

So, how do you get a list of queries?

pt-query-digest can use a slow query log, binary log, general log or tcpdump. I usually use a slow query log with long_query_time set to 0, so I can capture all the …

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Barcelona MySQL Users Group Meetup on 5th July

If you’re in Barcelona next week you may be interested in the MySQL Meetup being held there by the Barcelona MySQL Meetup group on Wednesday 7th July at 7pm. I’ll be doing a talk on MySQL Failover and Orchestration and there will be opportunity to talk about MySQL and related topics afterwards. More information can … Continue reading Barcelona MySQL Users Group Meetup on 5th July

Why does the MySQL optimizer not do what I think it should?

In May, I presented two talks – one called “Are you getting the best out of your indexes?” and “Optimizing Queries Using EXPLAIN”. I now have slides and video for both of them.

The first talk about indexing should probably be titled “Why is MySQL doing this?!!?!!?” It gives insight into why the MySQL optimizer chooses indexes that you do not expect; especially when it does not use an index you expect it to.

The talk has something for everyone – for beginners it explains B-trees and how they work, and for the more seasoned DBA it explains concepts like average value group size, and how the optimizer uses those concepts applied to metadata to make decisions.

Slides are at http://technocation.org/files/doc/2017_05_MySQLindexes.pdf.
Click the slide image below to go to the video at …

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Percona Live 2017

So glad to have had a successful Percona Live last week. Continuent were Diamond Sponsors and now that we are back into a company and not part of VMware we have a little more freedom to get back into the MySQL community.

I had two primary sessions, both on the replicator/ But one was looking specifically at the replicator and how we get data into Big Data targets, the other on general problems of replicating between heterogeneous sources. After the first of those, David from Percona interviewed me to understand a bit more about what I was talking about

I was also on the keynote panel where we discussed a variety of different …

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Percona Live Featured Session with Casper Kejlberg-Rasmussen: Placing Databases @ Uber

Welcome to another post in the series of Percona Live featured session blogs! In these blogs, we’ll highlight some of the session speakers that will be at this year’s Percona Live conference. We’ll also discuss how these sessions can help you improve your database environment. Make sure to read to the end to get a special Percona Live 2017 registration bonus!

In this Percona Live featured session, we’ll meet Casper Kejlberg-Rasmussen, Software Developer at Uber. His session is Placing Databases @ Uber. Uber has many thousands of MySQL databases running inside of Docker containers on thousands …

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Testing MySQL/MariaDB/Percona versions with Docker

Giuseppe Maxia has provided some great MySQL docker images. Percona and MariaDB also provide version via Docker Hub. In an attempt to have a consistent means of launching these different images I created the following convenience functions.

  1. Install docker for your OS. See Official Docker installation instructions.
  2. Get dockerhelper.sh
  3. Run your desired variant and version.

$ wget https://raw.githubusercontent.com/ronaldbradford/mysql-docker-minimal/master/dockerhelper.sh
$ . ./dockerhelper.sh
Docker …
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MMUG16: MySQL document store: SQL and NoSQL united

The Madrid MySQL Users Group has its next meeting on Tuesday, 22nd November 2016.  Giuseppe Maxia will be giving a presentation MySQL document store: SQL and NoSQL united and I’ll be providing a brief summary of the new MySQL 8.0 and MariaDB 10.2 beta versions which were announced recently. There will also be an opportunity to … Continue reading MMUG16: MySQL document store: SQL and NoSQL united

Juggling Databases Between Datacenters

    Recently we went through an exercise where we moved all of our database masters between data centers. We planned on doing this online with minimal user impact. Obviously when performing this sort of action there are a variety of considerations such as cache consistency and other pieces of shared state in stores like HBase, but the focus of this post will be primarily on MySQL.

    During this move we had a number of constraints. As mentioned above this was to be online when serving production traffic with minimal user impact. In aggregate we service hundreds of thousands of database queries per second. Additionally we needed to encrypt all data transferring between data centers. MySQL replication supports encryption, but connections to the servers themselves present several challenges. Specifically, from a performance standpoint the handshake to establish a connection across a WAN can impact latency if …

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OOW16 talk – MySQL X protocol – Talking to MySQL directly over the Wire

Oracle Open World 2016 has just finished in San Francisco and we are now about to embark on Percona Live Europe in Amsterdam. I offered a presentation in San Francisco on the MySQL X protocol, the new protocol that Oracle is using to make the DocumentStore work. This new protocol also allow you to send … Continue reading OOW16 talk – MySQL X protocol – Talking to MySQL directly over the Wire

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